The catalytic dehydrogenation of aliphatic C—H bonds is of major industrial importance. During the past decade there has been a steady progress in the development of soluble transition metal complexes as catalysts for the dehydrogenation of alkanes at moderate conditions. U.S. Pat. No. 5,780,701 discloses an iridium (III) catalytic system (PCP)IrH2 [PCP=η3—C6H3(CH2P(But)2)2)—1,3], a highly active, homogeneous catalyst for the dehydrogenation of cylcoalkanes at about 200° C. Iridium and rhodium complexes PCP pincer ligands have unusually high thermal stabilities. The key to their effectiveness appears to be their long-term stability even at 200° C. However the production of terminal olefins via the pincer catalyst is limited by the required consumption of a stochiometric amount of a sacrificial hydrogen acceptor and also by the secondary catalytic isomerisation of the terminal olefin to internal isomers.